Field of the Disclosure
The present invention relates to a display panel and a method for manufacturing thereof, and more particularly, to a display panel having a slim profile and low reflectance for an external light and good external visibility, and a method for manufacturing thereof.
Discussion of the Related Art
Recently, display panels, such as liquid crystal display (LCD) and organic light emitting diode display (OLED), have attracted as great attentions as flat display panels.
Especially, the display panels using an organic light emitting diode are advantageous in that they have no need for an additional light source, and they realize good picture quality and low power consumption.
The display panel using the organic light emitting diode is realized by forming a thin film transistor (TFT) and an organic light emitting layer on a substrate. If using a white organic light emitting device, a color is expressed by the use of color filter.
The display panel using the color filter and the white organic light emitting device may be formed in a 3-subpixel structure comprising red, green and blue sub pixels, or a 4-subpixel structure comprising red, green, blue and white sub pixels.
In case of the 4-subpixel structure comprising the red, green, blue and white sub pixels, a white color may be expressed on the display panel by driving only the white sub pixel without driving the red, green and blue sub pixels, to thereby reduce power consumption of the display panel.
However, a color filter layer is not required for the white sub pixel. Thus, there may be a problem relating a light reflection by a pixel internal electrode for an external light. Also, there may be a problem relating visibility to a user using the display panel due to the increase of reflectance for an external light. In order to overcome the problem relating the visibility caused by the reflectance for an external light, a polarizing plate (pol) may be provided in the display panel.
However, since the polarizing plate is thick, and is not flexible, the display panel is increased in its thickness due to the polarizing plate, and a manufacturing cost of the display panel is increased. Furthermore, it is difficult to realize a flexible display panel.
In case of the display panel using the organic light emitting device and including the white sub pixel, the color filter layer is not formed in the white sub pixel, whereby an internal reflectance for the external light in the white sub pixel is relatively higher than that of a neighboring sub pixel.
An incidence and reflection path of the external light in the white sub pixel will be described in brief. First, the external light is incident on the organic light emitting device via a substrate, and then the incident light is reflected on a common electrode of the organic light emitting device to the outside.
For improvement of visibility by the external light, the polarizing plate may be additionally provided outside the substrate so as to reduce the reflectance. In this case, the manufacturing cost of the device is increased due to the polarizing plate. Also, since the polarizing plate is thick and is not flexible, it is difficult to realize the flexible display panel with slimness.